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A critical obstacle in tissue engineering is to develop a massive structure of living cells upon transfer from the in vitro culture conditions into the host in vivo. A vascular network is required to supply essential nutrients, including oxygen, remove metabolic waste products and provide a biochemical communication “highway”. For these reasons to build an implantable structure in which vessel formation (angiogenesis) take place is mandatory. PLLA scaffolds usable in vascular tissue engineering were generated by dip-coating via Diffusion Induced Phase Separation (DIPS) technique. The scaffolds, with a vessel-like shape, were obtained by performing a DIPS process around a nylon fibre whose diameter was 700 μm. The fibre was first immersed into a 4% PLLA dioxane solution and subsequently immersed into a second bath containing distilled water. The covered fibre was then washed in order to eliminate the excess of dioxane and dried; finally the internal nylon fibre was pulled out so as to obtain a hollow biodegradable PLLA fibber. By Scanning Electron Microscopy observation the scaffolds have a lumen of ca. 700 μm and the internal surface show to be homogeneous with micro-pores of about 1-2 μm diameter. Moreover, a cross section analysis showed an open structure across the thickness of the scaffold walls. Inside the generated scaffolds we have cultured human endothelial cells; these have shown to be able to grow within the scaffolds and after 3 weeks they begin to form a “primordial” vessel-like structure, showing a well differentiate epithelial tissue.

In this study a chemical grafting procedure was set up in order to link high molecular weight poly L-lactic acid (PLLA) chains to the hydrophilic α,β-poly(N-2-hydroxyethyl)-DL-aspartamide (PHEA) backbone. A graft copolymer named PHEA-g-PLLA (or simply PHEA–PLLA) was obtained bearing a degree of derivatization of 1.0 mol.% of PLLA as grafted chain. This new hybrid derivative offers both the opportune crystallinity necessary for the production of scaffolds trough a thermally induced phase separation (TIPS) technique and the proper chemical reactivity to perform further functionalizations with bio-effectors and drugs. PHEA–PLLA porous scaffolds for tissue engineering applications were successfully obtained via TIPS and characterized. Structures with an open porosity and a good level of interconnection were detected. As the applicability of the scaffold is mainly dependent on its pore size, preliminary studies about the mechanisms governing scaffold's pore diameter were carried out.

Classe proposta A61F - Filtri da inserire nei vasi sanguigni; protesi; apparecchi ortopedici e curativi per contraccezione; fomentazione; trattamento o protezione degli occhi e delle orecchie; bendaggi, garze per medicazioni e assorbenti; necessario per il pronto soccorso

In this work, the possibility to produce composite - Poly-L-lactic acid (PLLA) and Hydroxyapatite (HA) - porous scaffolds via Thermally Induced Phase Separation for bone tissue engineering applications was investigated. Several PLLA/HA ratios were tested (70/30, 50/50, 30/70 and 20/80 wt/wt) and the as-obtained scaffolds were characterized via Scanning Electron Microscopy (SEM), Wide Angle X-Ray Diffraction (WAXD) and compression test. The results showed that the presence of HA does not influence the phase separation process. Morphological analysis revealed an open structure with interconnected pores and HA embedded in the polymer matrix. This evidence was confirmed by WAXD analysis; where the typical peaks of PLLA and HA appear. Finally, an increase of the young modulus was observed in the composite scaffolds with respect to pure PLLA scaffolds.